I also had truble with getting high with slow value RAM, even using divider. Get faster RAM!
But you can run the HTT quite high with lower mult, so this indicicates that the core is the limitation. Try higher voltage, and use ram divider.
166MHz RAM divider and 240MHz HTT x 10 should give 200MHz RAM and 2.4GHz CPU freq
Set HTTmult to 3x.
Use Memtest86 with these setting to see if the RAM is stable before running windows. If not stable, try a lower CPU mult. If stable then, the RAM is running OK. If not, you have a problem. Also try to change the RAM voltage. Never use default RAM settings. Allways test RAM stability first!